GGU-CAD: Circle and ellipse
Go either to the menu item "Draw/Circle" or "Draw/Ellipse". In terms of their size a circle and an ellipse are defined by two mouse clicks. The centre point of the circle or the ellipse is then positioned using the left mouse button.
Circles and ellipses are composed of several individual line segments. The number of segments is specified in the menu item "Preferences/Circle/Ellipse".

A minimum of 3 segments can be defined. A triangle would be drawn in this case. Defining a start angle is then practical, because this influences the orientation of the triangle.